The code in Context("Matrix") appears to work and produces the right answers, but I get the error message
PG warning message------
---- main (eval 982) 774 ------This does not appear to be a matrix
The code appears below
DOCUMENT(); # This should be the first executable line in the problem.
loadMacros(
"PG.pl",
"MathObjects.pl",
"PGbasicmacros.pl",
"PGanswermacros.pl",
"PGmatrixmacros.pl",
"PGcourse.pl",
);
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
Context("Matrix");
$a=non_zero_random(-3,3,1);
$c=non_zero_random(-3,3,1);
$b=-$c-2+$a*$c;
$A = Matrix([$a, $b, 1], [-1, 1, -1], [1, $c, 0]);
$A_inv = Compute($A->inverse);
BEGIN_TEXT
This problem is related to Problem 5.21 in the text.
$PAR
Given the matrix $BR
A = \{ mbox( display_matrix($A), "," ) \}
$BR
(a) does the inverse of the matrix exist?
$BR
Your answer is (input Yes or No): \{ans_rule(15) \}
$BR
(b) if your answer is Yes, write the inverse here; if the answer is NO, enter all zeros here:
$BR
\( A^{-1} = \) \{ mbox( answer_matrix(3,3,10), "." ) \}
END_TEXT
$ans0 = "Yes";
ANS(str_cmp($ans0));
ANS num_cmp(ra_flatten_matrix($A_inv));
Context()->texStrings;
SOLUTION(EV3(<<'END_SOLUTION'));
$PAR
$BBOLD SOLUTION $EBOLD
$PAR
The matrix is invertible $BR
\( A^{-1} = \) \{ mbox( display_matrix($A_inv) )\}
END_SOLUTION
ENDDOCUMENT(); # This should be the last executable line in the problem.
loadMacros(
"PG.pl",
"MathObjects.pl",
"PGbasicmacros.pl",
"PGanswermacros.pl",
"PGmatrixmacros.pl",
"PGcourse.pl",
);
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
Context("Matrix");
$a=non_zero_random(-3,3,1);
$c=non_zero_random(-3,3,1);
$b=-$c-2+$a*$c;
$A = Matrix([$a, $b, 1], [-1, 1, -1], [1, $c, 0]);
$A_inv = Compute($A->inverse);
BEGIN_TEXT
This problem is related to Problem 5.21 in the text.
$PAR
Given the matrix $BR
A = \{ mbox( display_matrix($A), "," ) \}
$BR
(a) does the inverse of the matrix exist?
$BR
Your answer is (input Yes or No): \{ans_rule(15) \}
$BR
(b) if your answer is Yes, write the inverse here; if the answer is NO, enter all zeros here:
$BR
\( A^{-1} = \) \{ mbox( answer_matrix(3,3,10), "." ) \}
END_TEXT
$ans0 = "Yes";
ANS(str_cmp($ans0));
ANS num_cmp(ra_flatten_matrix($A_inv));
Context()->texStrings;
SOLUTION(EV3(<<'END_SOLUTION'));
$PAR
$BBOLD SOLUTION $EBOLD
$PAR
The matrix is invertible $BR
\( A^{-1} = \) \{ mbox( display_matrix($A_inv) )\}
END_SOLUTION
ENDDOCUMENT(); # This should be the last executable line in the problem.